Oil-soluble mixed copper soap products

ABSTRACT

OIL-SOLUBLE MIXED COPPER SOAPS OF STRUCTURALLY DIFFERENT ORGANIC MONOCARBOXYLIC ACIDS, THE ACIDS BEING SELECTED FROM THE GROUP CONSISTING OF SATURATED ALIPHATIC ACIDS AND OLEFINIC ACIDS, AND SOLUTIONS OF SUCH MIXED SOAPS ARE PROVIDED.

United States Patent 3,701,729 OIL-SOLUBLE MIXED COPPER SOAP PRODUCTSAlfred Fischer, Bronx, N.Y., and Terry M. Strawser, iSonnd Brook, N.J.,assignors to Tenneco Chemicals nc. No Drawing. Filed June 1, 1970, Ser.No. 42,536 Int. Cl. C10m 3/18, 5/14 US. Cl. 252-1 28 Claims ABSTRACT OFTHE DISCLOSURE Oil-soluble mixed copper soaps of structurally differentorganic monocarboxylic acids, the acids being selected from the groupconsisting of saturated aliphatic acids and olefinic acids, andsolutions of such mixed soaps are provided.

It is desirable for many purposes to be able to obtain dissolvedcopper-containing hydrocarbon oils. Such dissolved copper is generallyobtained by dissolving or dispersing an oil-soluble copper soap into thehydrocarbon oil. Such dispersed copper is especially useful in fuel oilsfor removing or preventing the deposition of soot when burning the oilin furnaces or other equipment such as locomotives and fire-up torches.Oil-soluble copper soaps are also useful as a source of soluble copperfor use as catalysts for various liquid phase organic reactions, e.g.the preparation of adipic acid, and for the preparation of fungicidesfor use in oils or oil-miscible materials.

It has been recognized, heretofore, that various copper soaps areoil-soluble, including the copper soaps of the petroleum acids, i.e. thesulfonic acids, often referred to as the mahogany acids, and thenaphthenic acids. These materials, however, are generally of arelatively high molecular weight so that in order to obtain a desiredpercentage of copper, by weight, dissolved in the oil, it was necessaryto dissolve a relatively high percentage of the total soap in the oil.

Accordingly, it is desirable to use lower molecular weight copper soapsin order to obtain a higher proportion of copper dissolved for a givenamount of soap added. Johnson, in US. Pat. No. 2,622,671, describescopper soaps of certain lower molecular weight acids which are solublein turpentine and which can then be dissolved in fuel oils. Johnsondescribes these as the salts of branched chain acyclic aliphaticcanboxylic acids having from 5 to 12 carbon atoms, in which the carboxylgroup is attached to a carbon atom other than the central carbon atom inthe longest hydrocarbon chain. It has been found, however, that all suchsoaps are not generally soluble in hydrocarbon nonpolar solvents, suchas mineral spirits; Johnson asserts they are soluble in turpentine andthen miscible with other materials. As these other nonpolar solvents aregenerally much less expensive to obtain or produce than turpentine, and,therefore, more likely to be commercially useful in such low cost, highvolume uses as fuel oils, the need remains to obtain materials thatprovide a relatively high concentration of copper for as small a totalamount of soap added as possible in an oil-miscible environment.

The present invention is directed to an oil-soluble mixed copper soapproduct comprising one or more soaps containing combined copper withacid groups derived from two structurally difierent organicmonocarboxylic acids selected from the group consisting of saturated andolefinically unsaturated aliphatic carboxylic acids. This inventionfurther provides a solution comprising a nonpolar hydrocarbon solvent ora halo-substituted nonpolar hydrocarbon solvent having dissolved thereinthe oil-soluble mixed copper soap composition as defined above.

The present invention includes an oil-soluble copper mixed soapcomprising copper combined with two structurally diiferent acid groupsderived from the organic monocarboxylic acids defined above, and stablesolutions of the copper mixed soaps in a nonpolar hydrocarbon solvent orchlorinated nonpolar hydrocarbon solvent.

This invention further includes a coprecipitated mixture of copper soapsof two structurally different carboxylic acids selected from the abovegroup consisting of saturated and olefinically unsaturated aliphaticmonocarboxylic acids; a solution comprising a nonpolar hydrocarbonsolvent or halo-substituted nonpolar hydrocarbon solvent containingdissolved therein a mixture of such salts is also a part of thisinvention.

The copper mixed soap product of this invention can broadly be preparedby the process comprising simultaneously reacting copper, in the form ofcombined or elemental copper, with acid group-containing compounds,there being present at least two structurally dilferent acid groups, asdefined above. It is, however, often not possible to determine theprecise structure of the product according to this process, i.e. whetherit is a copper mixed soap, a coprecipitated mixture of two normal soaps,or a coprecipitated combination of a mixed soap and the two normalsoaps. In such circumstances, defining the product in terms of the abovepreparation process is a complete definition of the product.

The mixed copper soap products of the present invention are in the formof a copper mixed soap or of the coprecipitated soap. The coprecipitatedsoaps can be prepared from a mixture of normal soaps, that are dissolvedpreferably from an intimate mixture, as by finely grinding together, andthen removing the solvent.

The term normal soap when used herein refers to the copper soap of asingle acid, e.g. copper 2-ethylhexoate. The term coprecipitated soapswhen used herein, refers to a combination of two copper soaps obtainedby removing the solvent from a solution of the two soaps or by causingthe simultaneous precipitation of the two soaps from a solution of thetwo soaps.

In the preferred embodiments of this invention, the normal copper soapsof the acids used are insoluble but the mixed soap products of thisinvention are oil-soluble, i.e. soluble at room temperature in nonpolaroil miscible liquids, to form a solution stable at room temperature.

The copper mixed soap and coprecipitated copper soaps of this inventionare generally more readily dissolved in oils and nonpolar hydrocarbonsolvents and halo-substituted nonpolar hydrocarbon solvents than aremere mixtures of the normal copper soaps of the same acids. In addition,the solutions containing the dissolved copper soaps show a decreasedviscosity when the mixed copper soap products are present as compared tothe viscosity when only one of the normal copper soaps of the same acidsis soluble and is dissolved in the same total propertions. There is alsogenerally an improvement in the viscosity of the final solution comparedto solutions obtained from normal copper soaps that are soluble. Thisdecrease in viscosity results in an improved product which can be morereadily handled and more easily mixed and otherwise processed.

It has been found that the isolated copper mixed soaps andcoprecipitated soaps of the present invention behave differently than amixture of the normal copper soaps of the same two structurallydifierent acids. The copper mixed soaps and coprecipitated soaps of thepresent invention are not crystalline granular material as are thenormal copper soaps of most of these acids, but rather, appear as a softplastic mass, noncrystalline in appearance. A mechanical mixture of thecopper soaps of the same acids does not dissolve in a nonpolar solventas readily as the mixed soap in many instances. But many mixtures ofsoaps can generally be dissolved by heating, e.g. in mineral spirits,generally to form a stable solution. The coprecipitated soaps can, ofcourse, then be obtained by evaporating off the solvent. Accordingly,mixed copper soap products of this invention include broadly, all thesetypes.

The copper mixed soaps of the present invention are believed to have thefollowing structure:

OOC-R wherein R and R are structurally different and selected from amongsaturated aliphatic and olefinically unsaturated aliphatic groups. TheRCOO and R'COO groups are the residue of the correspondingmonocarboxylic acids. In the so-called normal soaps, R and R are thesame. The group of acids is sub-divided into the following differentstructural groups. For example, the broad group: saturated aliphaticacids and olefinic acids, is subdivided according to whether there isbranching, and if so, the position of the branch closest to the carboxylgroup: these include the straight-chain acids, e.g. normal octanoic acidor caprylic acid, the alpha-substituted branched acids, e.g.Z-ethylhexanoic acid, the beta-substituted branchedchain acids, e.g.3,5,5 trimethylhexanoic acid and the gamma-substituted branched acids,e.g. 4 ethyl 5,-5-dimethylhexanoic acid and delta-substituted, e.g.5-ethyl-6- methylheptanoic acid. The position of, or even the existenceof, further branching on the chain more than five carbon atoms removedfrom the carboxyl group has been found to have little or no effect informing an oil-soluble mixed salt or a lower viscosity solution whenmixed with a linear chain acid.

The alpha acids contain a first branched chain on the first carbon atomadjacent to the carboxyl group. The beta acids contain a first branchedchain attached to the second carbon atom removed from the carboxylgroup. In the gamma acids, the first branched chain is attached nocloser than the third carbon atom from the carboxyl group.

Generally, the acid groups present in the copper mixed soap product orcoprecipitated soaps of the present invention have at least five carbonatoms in the molecule. Preferably, the acid groups will have from about5 to about 20 carbon atoms, the upper limit not being a limit as to theeffectiveness of the material in forming a soluble soap but rather asreaching a point where the proportion of copper in the molecule is solow as to render uneconomical the use of such a soap as a source ofcopper. The optimum acid groups contain from about 6 to about 11 carbonatoms.

Generally, the most useful compounds are the hydrocarbon acids becausethese are the most readily available at the lowest prices. However, themixed copper soaps or coprecipitated soaps of this invention alsoinclude the soaps of acids which contain various inert substituentgroups attached onto the hydrocarbon chain, or side chain. Such inertsubstituent groups include, particularly, the halogen atoms, andespecially chlorine, and oxygen atoms in the form of ether linkagesalong the chain of the carboxylic acid or in one of the branch chains.

Useful aliphatic acids are those having at least five carbon atoms andinclude the saturated linear fatty acids, such as valeric acid, caproicacid, caprylic acid (noctanoic), pelargonic acid, n-decanoic acid,undecanoic acid and lauric acid. The alpha-branched saturated acidsinclude Z-ethyI-butanoic acid, 2-ethyl-4-methylpentanoic acid,2-ethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid,2-isopropyl-2,3-dimethylbutanoic acid, 2-propyl-4- methylpentanoic acid,2-propylheptan0ic acid, Z-methylbutanoic acid, Z-methylpentanoic acid,2,3-dimethy1pentanoic acid, 2,2-dimethylpentanoic acid,2-ethyl-3-methylbutanoic acid, 2,5-dimethylhexanoic acid,2,2-dimethylheptanoic acid, 2-ethyl-5-methylhexanoic acid,2-methylnonanoic acid, 2-ethyloctanoic acid, 2-propylhexanoic acid,2-propyl-5-methylhexanoic acid. Beta branched acids include3-methylb-utanoic acid, 3,3-dimethylbutanoic acid, 3,3-dimethylpentanoicacid, 3-ethylpentanoic acid, 3,5-dimethylhexanoic acid,3-ethyl-4-methylpentanoic acid, 3- methylactanoic acid, 3 propylhexanoicacid, 3,5,5-trimethylhexanoic acid, 3 ethylnonanoic acid. The gamma anddelta branched acids include 4 methylpentanoic acid, 4 methylhexanoicacid, 5 methylhexanoic acid, 5 methylheptanoic acid, 4 ethyloctanoicacid, 4 ethyl 5,5 dimethylhexanoic acid, 4 methyldecanoic acid and4,8-dimethylnonanoic acid. Olefinically unsaturated monocarboxylic acidsinclude 4-pentenoic acid, 3-hexenoic acid, 2-ethyl-2-hexenoic acid and10 undecenoic acid.

The presence or absence of unsaturation is not relevant to structuraldifference. The presence and position, if present, of branchingdetermines structural difference, e.g. l0-undecenoic acid isstructurally the same as n-nonanoic acid.

Generally, the saturated aliphatic 'monocarboxyclic acids are preferredfor the practice of this invention as they are the most generallyavailable and, therefore, the most economical acids to be used in thepreparing of soluble copper mixed salts.

The mixed copper soaps of the present invention can generally beprepared by reacting a source of copper, i.e. copper metal or a coppercompound, including a salt or a hydroxide, with the desired organicacids or soluble salts of the acids, especially the sodium salts. Thereactions are preferably carried out in a nonpolar oil-miscible solventso as to directly prepare the ultimately desired oilrniscibleconcentrated solution of copper. However, the reaction can also becarried out in an alcohol and/or water environment and the mixed soapseparated as a solid before being dissolved.

Preparation from elemental copper can be carried out as follows:particulate finely divided copper metal plus two structurally differentorganic acids, as defined above, are dispersed in a mineral spiritssolvent together with water. The mixture is heated to from about 60 toC. and is maintained at the temperature while it is agitated and air oroxygen is blown through the mixture as an oxidizing agent. The water isthen distilled off after reaction is complete, leaving the solution ofthe mixed copper salt in the mineral spirits solvent. The generalreaction equation is as follows:

wherein HA and HB are the structurally different acids.

A second method for preparing the copper mixed soap is by the reactionof cupric hydroxide with a mixture of the two organic carboxylic acidsin mineral spirits solvent to prepare a solution of the mixed coppersalt. Sufiicient amounts of the copper hydroxide and of the two acidsare dispersed in mineral spirits to produce the desired concentration ofcopper in the final solution and reaction takes place at from about 30to 70 C. The reaction mixture is then heated to above the boiling pointof water formed. The final mineral spirits solution can then be useddirectly as a source of dissolved copper. The cupric hydroxide reagentwhich is used can also be a carbonated material having a formula (CuCO-Cu(OH) The copper mixed salt can also be obtained from a doubledecomposition reaction, where cupric sulphate is reacted with a mixtureof the sodium salts of the two desired acids in an aqueous system toform a mixture of the mixed copper soap plus sodium sulphate. The sodiumsulphate remains in solution in the Water system and the copper mixedsoap precipitates out and is thus readily separated.

Another procedure for preparing these materials is as follows: asaturated solution of copper acetate and hot water is treated with hotethanol. Before a precipitate can form a warm alcoholic solution of thetwo desired organic acids is added and the resulting solution kept Warmfor about 15 minutes. The mixed soap is then separaetd from the solventby suitable means.

In each of the above procedures the acid groups are preferably presentin equimolar proportion; preferably the mixed acids are present slightlyin excess of the amount of the copper present, preferably from to 15percent of molar excess. The presence of additional acid, of course,does not interfere with the reaction but is wasteful.

The acids can, if desired, be mixed in other than equimolar proportions;however, this will result in a product which is actually a mixture ofthe copper mixed soap plus the copper soap of whichever acid is presentin excess. Such a mixture of the mixed soapplus additional copper salthas been found to be soluble for mixtures containing up 200 percentmolar excess of one of the acids. The excess amount of any acid that canbe tolerated and still obtain a soluble product is at least in partdependent upon the solubility, in the mineral spirits or oil, of thesalt of the acid present in excess. Even the most insoluble acid saltcan be present in excess to a certain degree, apparently through somesort of solubilizing effect of the mixed soap. Preferably the maximumamount of excess is about 150 percent. Generally, even those acids thatform the most insoluble salts of copper can be present up to about 50percent in excess to form excess normal copper salt of that acid. Theamount of the normal copper salt dissolved in the mineral spirits whenformed from the excess acid can be above that which would be noramllysoluble in the nonpolar solvent, but it is soluble when present insolution with the mixed copper soap of the present invention.

In Whatever form the copper and the structurally different acids arecombined, i.e. as a true mixed salt, as a mixture of normal salts, or asa mixture of one or two normal salts and a mixed salt, the molar ratioof copperzacid type A:acid type B, preferably is 1:'0.81.2: 1.2-0.8. Ifthere are more than two different acid groups present, but only twostructural types of acids, e.g. n-octanoic, n-nonanoic andZ-ethylhexanoic acid, the acids of the same type are added together todetermine the proportion of that type present. For example, 0.5 mole ofn-octanoic acid, 0.6 mole of nnonanoic acid, and 1.1 moles of2-ethylhexanoic acid, gives a ratio of acid type Azacid type B of 1:1.

The copper mixed soap of the present invention is believed to exist as atrue compound and not merely a solid solution of the two normal salts.Based upon the equilibrium distribution of products from these chemicalreactions, however, a mixture of the mixed salt plus proportions of thenormal copper salts of each of the two acids is probably present.Accordingly, the copper mixed soap of the present invention can also bedefined by the method by which it is prepared: a copper soap prepared bythe simultaneous reaction with copper of the groups of two structurallydilferent organic monocarboxylic acids, of the acids defined above. Thecoprecipitated copper salts which are also soluble in the proportionsfound for the mixed salts can be formed from the solutions ofindividually prepared normal salts that are mixed and thencoprecipitated. Generally, when the normal copper salts of any one ofthe above defined acids are prepared by the methods described above inmineral spirits solvent, an unstable solution is formed, from which thecopper soap precipitates at varying times after cooling to roomtemperature. If the solutions were mixed before precipitation, a stablesolution is formed; especially where the copper soaps are present inequimolar amounts, or within the range of excess described above for themixed salt. When the solvent is removed to form a coprecipitate, thecoprecipitate can be redissolved to form a stable solution.

Also, generally, the mixed soaps or coprecipitated soaps, can beprepared by any method used for the preparation of the normal coppersoaps, merely substituting a mixture of two structurally differentacids, preferably in about an aquimolar mixture, as explained above, toform the desired mixed acid soap. For such normal soap preparations see,for example, US. Pats. Nos. 2,584,041 and 2,113,496.

Generally, the alpha-branched saturated aliphatic carboxylic acids andthe straight chain aliphatic acids provided salts of copper having thelowest solubility. The beta and the gamma-branched acids have somewhathigher solubilities in mineral spirits or other nonpolar hydrocarbonsolvents; therefore the alpha-branched and straight chain acids shouldnot be tolerated in as great an excess before precipitation would occurfrom an oil solution as the more soluble salts of the beta or gammaacids. Further, the copper salts of the branched chain acids having aquaternary carbon atom at the terminal point of the chain furthest awayfrom the carboxyl group tend to be as insoluble as the salts of thealpha acids. A surprising aspect of the present invention, is that themixed salts formed from mixtures of alpha-branched and straight chainsaturated aliphatic acids are substantially as soluble as are the mixedsalts formed from an alpha-branched and a betabranched acid or the mixedsalt of a beta and a gamma acid, etc.

The oil-soluble mixed copper soap of the present invention is soluble ina hydrocarbon nonpolar solvent or halogenated such solvent. Thehydrocarbon solvents include the liquid distillates, or mineral spirits(hydrocarbon distillates), such as gasoline, kerosene, the diesel fuels,1, 2, and 3, the higher-boiling distillates, known as fuel oils 4, 5 and6, as well as aromatic hydrocarbon oils. In addition, the mixed soapsare soluble in fuels which become liquid only when pre-heated, such ashigher melting residual oils which are semi-solid in nature and must beheated to temperatures of the order of F. to increase their fluiditybefore they may be used as burning fuels of the liquid type. Othernon-petroleum derivatives solvents for the oil-soluble mixed coppersoaps include xylene, turpentine, toluene and ethyl benzene.

Useful chlorinated organic solvents include o-dichlorobenzene, carbontetrachloride, ethylene dichloride and perchloroethylene.

As state above, the use of halogenated, e.g. chlorinated, acid iscontemplated in the preparation of the mixed soap. The halogenated acidsare not now sufliciently low in cost so as to be economically useful asan additive for a fuel oil. If in the future such chlorinated acids dobecome cheaply available, or if, in specific instances, there are suchhalogenated acids available as a side product or by-product from otherreactions, they can be usefully used in accordance with the suggestionof Johnson, US. Pat. No. 2,622,671 to improve the effectiveness of thesoot remover composition. Chlorinated organic compounds, generally, canprovide a source of chlorine in the concentrate. The chlorine reactswith copper to reduce soot formation apparently by lowering the ignitiontemperature of soot deposits. Johnson suggests adding a separatechlorinated organic compound. However, where chlorinated acids areavailable, one of these could be used to form the mixed soap and anotherstructurally different organic acid, or halogenated such acid, in lieuof a mixture of the soap plus a separate chlorinated hydrocarboncompound.

The following examples represent certain preferred embodiments of thepresent invention and the preparation of certain of the mixed soaps andmineral spirit concentrates containing the mixed soap dissolved inproportions of approximately 8 to 10 percent by weight of copper. Theusual concentration of the mixed copper soap product in mineral spiritsis about 6 to 15 percent by weight copper and preferably about 8 to 12percent copper.

7 COMPARATIVE EXAMPLES AM A series of normal copper soaps were preparedby the following procedure, using 2,2-dimethylpentanoic acid as anexample:

The acid (136 g.), mineral spirits (230 g.), and cupric hydroxide (49g.) were charged to a flask at room temperature, heated, with mechanicalagitation, to 75-80" C., and maintained at that temperature until all ofthe cupric hydroxide had dissolved. The mixture was then heated to 120C. to eliminate the water formed. Where there was no immediateprecipitation, the solution was diluted with mineral spirits to about 8percent by weight copper (to about 398 g. total weight of solution) andfiltered hot (l110 C.) to remove any unreacted copper hydroxide. Theseprocedures are carried out with about 4 percent excess acid, which tendsto promote solubility.

The appearance of the soap product obtained from each acid used is setout in Table 1, below. In each case the same amount of copper hydroxidewas used (49 g.):

8 mineral spirits solvent was permitted to cool by standing, and thefollowing results were observed.

Molar ratio of alpha acid to alpha plus beta acids: Observations 0.388Considerable dark green granular material.

0.5 Stable solutions.

0.756 s Some dark green material deposited.

EXAMPLE 3 TABLE I.-NORMAL COPPER SOAPS Grams oi-- Comparative AcidMineral example Acid group used spirits used Solubility of soap inmineral spirits solvent A 2,2-dimethylpentanoic 136 230 Partially)soluble in mineral spirits at room temperature (up to 2%, by wtcopper2-ethyl-4-methylpentanoic. 150 216 Crystallized IOU-120 C. 0..Z-ethylhexanoic 150 216 crystallized 95-105" 0. D2-propyl4-methylpentanoic-. 165 201 crystallized at 110120 C. E2-propylheptenoic 180 186 crystallized upon vooling to room temperature.F 2-ethyl-2-hexenoic 150 216 crystallized at 100l20 C. G3,5,5-trimethylhexanoic 165 201 Orystallized slowly upon aging at roomtemperature after 3 days. H 4-ethyi-5,5dimethylhexanoic 180 186solidified completely at room temperature. I -methyl pentanoic 121 245Orystallized upon cooling at room temperature. I n-Oetanoie 150 216solidified completely at room temperature' K n-Nonanoic 165 201 Do. L.10-undecenoic. 194 172 Do. M n-Hexanoic 121 245 Substantially allcrystallized at room temperature.

As shown by the results set out in Table I, none of the normal soaps ofcopper are sufiiciently oil-soluble to provide a stable solution inmineral spirits of 8 percent copper, and only one is soluble to morethan 1 percent copper. Four of the soaps solidified completely, forminga gel in the mineral spirits solvent.

EXAMPLE 1 A stable solution of an oil-soluble copper mixed soap wasobtained by mixing 1.07 g.-mols 2-ethylhexanoic acid, 1.07 g.mols,3,5,5-trimethylhexanoic acid and 1.0 mol copper hydroxide (Cu(OI-I) inmineral spirits. The materials were mixed and heated to from to 70 C.until reaction was substantially completed. The solution was then heatedto 120 C. to eliminate the water formed during the reaction, filtered toremove any unreacted copper hydroxide, and then diluted with sufiicientadditional mineral spirits to produce a solution containing 8 percent byweight of copper of the mixed copper carboxylates.

The clear solution was then concentrated by distillation to 10 percentby weight copper; the viscosity of this solution was determined to be E(1.25 stokes) on the Gardner- Holdt scale. The mineral spirits used inthis preparation had the following composition: 6.7% aromatics, 91.3%saturates and 2% olefins (Shell Mineral Spirits l4566 The solvent wasthen distilled OE and the solid mixed copper soap was obtained. Thesolid mixed soap was of a soft plastic consistency and was coloredgreen. The mixed soap was then completely redissolved at roomtemperature in additional mineral spirits to prepare a stable solutioncontaining 8 percent copper.

EXAMPLE 2 The procedure of Example 1 was repeated several times but ineach case using different proportions of the Z-ethylhexanoic acid (alphaacid) and 3,5,5-trimethylhexanoic acid (beta acid). The solution of themixed soap in the propeller agitator and fritted glass air injectiontube extending to the bottom of the flask. The copper and the acids weredispersed into the mineral spirits and the dispersion was then heated toC. Water (25 g.) was then added to the mixture and air blown through themixture while it was vigorously agitated. After the reaction had gone tocompletion, any remaining solid material was filtered out. The solutionwas vacuum distilled at C. and a pressure of 25 mm. Hg absolute, toremove any remaining water.

The mineral spirits solvent was evaporated to obtain the mixed soap ofcopper 2-ethylhexanoate/3,5,5-trimethylhexanoate. The solution wasdiluted with mineral spirits to a concentration of 10 percent copper, toform a dark green solution having the same properties as that obtainedin Example 1. This material readily dissolves in the mineral spirits toform the desired 8 percent by weight copper solution.

EXAMPLE 4 The mixed soap of 2-ethylhexanoic acid and3,5,5-trimethylhexanoic acid is also formed by the reaction of one molof cupric sulphate mixed with 1.07 mols each of sodium Z-ethylhexanoateand sodium 3,5,5-trimethylhexanoate. The sodium salts are dissolved inwater and heated to 70 C. The mixed soap of copper2-ethy1hexanoate/3,5,5-trimethylhexanoate precipitated out and isreadily separated as a soft plastic mass identical to that formed inExample 1. The solid material is dried and then readily dissolves in themineral spirits of Example 1 to form a stable solution.

EXAMPLE 5 One g-mol of copper acetate is dissolved to form a saturatedsolution in hot water. To this saturated solution is added 200 mls. ofhot ethanol at 70 C. Immediately thereafter, and before a precipitatecould form, a solution in alcohol of 1.11 g.-mols each of2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid is added to thecopper acetate solution which is maintained at 70 C. for about 15minutes. The alcohol and water mixture is heated away to leave the mixedcopper salt.

EXAMPLE 6 The procedure of Example 1 was followed but Z-ethyl-4-methylpentanoic acid is substituted for the 2-ethylhexanoic acid. Themixed copper soap of the two acids was obtained as a green plasticdeposit, which readily redissolved in mineral spirits to form an 8percent copper stable solution.

EXAMPLES 7-17 The procedure of Example 1 was followed but usingCOMPARATIVE EXAMPLE COMPARATIVE EXAMPLES P-R The procedure of Example 1was repeated, but substituting the acid pairs and amounts set forth inTable IH. Each pair of acids in Examples P-R, respectively, are in thesame structural group. The results obtained were as the acids and theproportions set forth in Table II, below. 15 follows:

TAB LE III Grams Comparative Acid Mineral Solubility of mixed soap inmineral example Acid pairs used spirits used spirits soiv ant P 2-ethylhexanoic 75 216 Crystallized at lilo-110 C.

2-ethyl-4-methyl pentanoic. 75 Q Z-ethyl hexanoic 75 216 Do.

2-ethyl-2-hexenoic 75 R 2-eth yl hexanoic 75 223 Orystallized partiallyat 100-110" 0.; more 2,2-d1methyl pentanoic. 68 upon cooling to roomtemperature.

In each case 49 g. of copper hydroxide was used, and a stable solutioncontaining 8 percent by weight of copper was prepared.

As shown, by each of Examples N-R, mixed soaps formed from two acidsthat are structurally the same are not oil-soluble where the normalcopper soap of each TABLE II Acid Grams of 8% Mineral copper solu- YieldExample Acids used (A) (g.) (B) (g.) spir1ts(g.) tion obtained (percent)(A) 2,2-dimethyl pentauoic 7 gfifil-tliliilethtlg liexantole aieidn} 685 382 0 e y me y pen ano e 8 "{(B) 3,5,5-trimethyl hexanoie acid 75 5 5385 8 (A) 4-ethyl-5,5-dimethyl 9 exam 0 82. 5 193. 5 393 98, 3

3,5I-trimelthy1hexanoie acid nonano c 3,5,5-timeth1y1 haxanoic acid. 5 5201 395 2 10-un eceno e n gjki-trihznfithyl l'iexanoic acid.- 97 5 5 3778 -e y exeno c 12 "{(B) 3,5,5-trimethyl hexanoic acid 5 5 (I) (a) (A)4-ethyl-5,5-dimethyl 13 75 201 395 99. 2

(I3 2-eItIhy1 he ranoic acid 11- onano c 14 iethtyll liexaniic aicidn. 575 5 392 5 me y pen ano c E2; 2 1 F Y 60.5 60.5 245 382 96.0

me y pen ano c 16 "{(2) idtfifitrlirlpeghyllhexanoie acid 5 5 223 381 7-e y u ano c 17 (B) 3,5,5-trimathyl h-sxanoic aeid 5 5 233 381 7 1Thick, but clear solution obtained. I Not determined; estimated over90%.

COMPARATIVE EXAMPLE N The procedure in Example 1 was repeated butsubstituting for the two acids used 2-ethylhexanoic acid and the mixedalpha acids known as Versatic 9 (56% 2,2,4,4-

tetramethylpentanoic acid and 27% 2-i sopropyl-2,3-di- 70 methylbutanoicacid). The material did not form a stable solution but immediatelyprecipitated out as a dark green granular copper soap. The precipitationoccurred at elevated temperatures of about 95 to C., even before thesolution could cool.

acid is insoluble in the mineral spirits solvent.

EXAMPLE 18 A freshly prepared solution of copper 3,5,5-trimethylhexanoate in mineral spirits as prepared in Comparative 60 Example G(398 g., 8% copper) was maintained at 100 C. and mixed with a solidifiedcopper 4-ethyl-5,S-dimethyl hexanoate solution (398 g., 8% copper) asprepared in Comparative Example H. The mixture was heated up to C. toform a uniform solution, and held there for 5 5-10 minutes. Thetemperature was cooled down to room temperature and the solutionremained clear and stable. A coprecipitate can be obtained byevaporating the mineral spirits solvent. The coprecipitate can bereadily redissolved in mineral spirits at room temperature.

EXAMPLES 19 AND 20 The procedure of Example 18 was repeated butsubstituting the salts in accordance with Table IV below. The mixture isdissolved at the temperature indicated in 75 Table IV to form a stablesolution in each case.

TABLE IV Dissolution tempera- Condition on cooling Example Salt A and(condition) Salt B and (condition) ture, C. to room temperature 19---Copper 3,5,5-trimethyl hexanoate Copper-nonanoate 2 80 Clear and stablesolution. 20 do Copper-caprylate/n-nonanoate 74 Do.

1 Solution (Example G).

2 solidified solution (Example K).

3 solidified solution (Example Both Examples 19 and 20 formed solutionsof the mixed salts that were clear and stable. They could be evaporatedto form a coprecipitated mixture of salts that could be redissolved inmineral spirits solvent.

EXAMPLE 21 A stable, clear solution in o-dichlorobenzene of anoilsoluble mixed copper soap product was obtained by mixing 1.07 g.-mols2,2-dimethylpentanoic acid, 1.07 g.-mols 3,5,5-trimethylhexanoic acidand 1.0 mol copper hydroxide (Cu(OH) in o-dichlorobenzene. The materialswere mixed and heated to from 30 to 70 C. until reaction wassubstantially completed. The solution was then heated to 120 C. toeliminate any water formed during the reaction and then diluted withsufficient additional o-dichlorobenzene to produce a clear greensolution containing 8 percent by weight of copper of the mixed coppersoaps.

EXAMPLE 22 The procedure of Example 21 was repeated but substitutingxylene for the o-dichlorobenzene. After preparing the solution, thexylene can be readily boiled away and the solid mixed copper soapobtained. The mixed soap was colored green and had a soft plasticconsistency. The mixed soap was then readily redissolved in xylene atroom temperature to prepare a stable solution containing 8 percentcopper.

The concentrated mineral spirit solutions of the mixed copper soapsprepared above are suitable for directly mixing with a fuel oil or otherhydrocarbon fuel to add the desired amount of the soluble copper as asoot remover additive. Generally, a concentrated solution containing 8percent by weight of the copper metal is added in a one part perthousand ratio to fuel oil; higher molecular weight, i.e. higher boilingpoint fuel oils, and the semi-solid so-called residual oils thatgenerally have a higher carbon content will require a somewhat higherpercentage or proportion of the concentrate perhaps from about one partper 200 to about 800 parts of the fuel oil. Broadly, the concentratedsolution is preferably added in a proportion of one part to from about200 to about 2000 parts of fuel oil.

The following is claimed as the patentable embodiment of the abovedefined invention:

1. An oil-soluble mixed copper soap product comprising combined coppercombined with acid groups derived from two structurally differentorganic monocarboxylic acids wherein the diflerence in structure isdefined in terms of the presence and position of branching in the acidgroups and wherein the acids are selected from the group consisting ofsaturated and olefinically unsaturated aliphatic acids, the normalcopper soaps of at least one of said acids being insoluble in oil atroom temperature.

2. The soap product of claim 1, wherein the aliphatic acids are selectedfrom the group consisting of straight chain acids, alpha-substitutedbranched chain acids, betasubstituted branched chain acids,gamma-substituted branched chain acids and delta-substituted branchedchain acids.

3. A stable solution containing at least 6 percent by weight ofdissolved copper comprising a solvent selected from the group consistingof nonpolar hydrocarbon solvents and chlorinated nonpolar hydrocarbonsolvents and an oil-soluble mixed copper soap product according to claim1.

4. Oil soluble mixed soap products in accordance with claim 1 whereinthe aliphatic acids contain from about 6 to about 11 carbon atoms.

5. An oil-soluble copper mixed soap of two structurally difierentorganic monocarboxylic acids wherein the difference in structure isdefined in terms of the presence and position of branching in the acidgroups and wherein the acids are selected from the group consisting ofsaturated and olefinically unsaturated aliphatic acids, the normalcopper soaps of at least one of said acids being insoluble in oil atroom temperature.

6. A mixed soap in accordance with claim 5, wherein the acids eachcontain at least five carbon atoms.

7. A mixed soap in accordance with claim 6, wherein the acids eachcontain from five to twenty carbon atoms.

8. A mixed soap in accordance with claim 5, wherein the acids compriseat least one saturated aliphatic acid.

9. A mixed soap in accordance with claim 8, wherein at least onesaturated aliphatic acid is an alpha or a betasubstituted branched chainacid or a straight chain acid.

10. A mixed soap in accordance with claim 8, wherein the acids compriseone alpha-branched and one betabranched saturated acid.

11. A mixed soap in accordance with claim 8, where the acids containfrom about six to about eleven carbon atoms.

12. A mixed soap in accordance with claim 5, wherein the acids compriseat least one olefinic acid.

13. A mixed soap in accordance with claim 12, wherein at least oneolefinic acid is an alpha or a beta-substituted branched chain acid or astraight chain acid.

14. A mixed soap in accordance with claim 5, wherein the acids areZ-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid.

15. The oil soluble copper mixed soaps in accordance with claim 5wherein the aliphatic acids contain from about 6 to about 11 carbonatoms.

16. An oil soluble mixed copper soap product containing combined copperand organic monocarboxylic acid groups derived from two structurallydifferent organic monocarboxylic acids wherein the dilference instructure is defined in terms of the presence and position of branchingin the acid groups and wherein the acids are selected from the groupconsisting of saturated and olefinically unsaturated aliphatic acids,the normal copper soaps of at least one of said acids being insoluble inoil at room temperature, the soap product being prepared by a processcomprising simultaneously reacting copper, in the form of eithercombined or elemental copper, with acid groupcontaining compoundscontaining two structurally difierent organic monocarboxylic acidgroups.

17. The compound of claim 16, wherein the acid group-containingcompounds are selected from the group consisting of the acids and thesalts of the acids.

18. The product of claim 16, wherein copper hydroxide is reacted with amixture of two structurally different acids.

19. The product of claim 16, wherein copper metal is reacted with amixture of two structurally different acids.

20. The product of claim 16, wherein a water-soluble copper salt isreacted with a mixture of the sodium salts of two structurally differentacids in an aqueous solution.

21. The product of claim 20, wherein the copper salt is copper sulphate.

22. The product of claim 16, wherein copper acetate is reacted with twostructurally different organic acids.

23. The product of claim 16, wherein the mol ratio of a first acid to astructurally different acid is from about 2:1 to 1:2.

24. An oil-soluble coprecipitated mixture of copper soaps of twostructurally different organic monocarboxylic acids wherein thedifference in structure is defined in terms of the presence and positionof brar iching in the acid groups and wherein the acids are selectedfrom the :group consisting of saturated and olefinically unsaturatedaliphatic acids, the normal copper soaps of; at least one of said acidsbeing insoluble in oil at room temperature, the coprecipitated mixturebeing sufiiciently soluble in mineral spirits to form a solutioncontaining by weight of copper.

25. The coprecipitated mixture of claim 24, wherein the mole ratio ofone structurally different acid group to a second structurally differentacid group being from about 2:1 to about 1:2.

26. A stable solution comprising a solvent selected from the groupconsisting of nonpolar hydrocarbon solvents and chlorinated nonpolarhydrocarbon solvents, combined copper and acid groups derived from twostructurally different organic monocarboxylic acids wherein thedifference in structure is defined in terms" of the presence andposition of branching in the acid groups and wherein the acids areselected from the groiip consisting of saturated and olefinicallyunsaturated aliphatic acids,

References Cited UNITED STATES PATENTS 2,584,041 1/ 1952 Nowak 260-97.52,528,803 11/ 19 Unkefer 260--97.5 2,373,387 4/1945 Elliott 260-97.5 X2,471,153 5/1949 Hoover 260-975 X 2,622,671 9/1953 Johnson 43133,446,737 5/1969 Panzer 252 ROBERT F. BURNETT, Primary Examiner M. E.MCCAMISH, Assistant Examiner US. Cl. X.R.

